The presence of a specific proteolytic enzyme will be sought at the site of bone resorption from cholesteatomas induced in guinea pigs and from human cholesteatoma containing resorbing bone. Organ cultures of guinea pig wound tissue and of human skin will be used to obtain collagenase which will be purifed and injected into rabbits to induce a specific antibody. This antibody will be tagged and incubated with a frozen section of cholesteatoma and bone enabling us to determine collagenase directly at the site of bone resorption in human and animal tissues. Epidermal cysts will be induced in the middle ear of guinea pigs in order to study the nature of the migrating squamous epithelium, the conditions leading to its ectopic position and the mechanisms by which it induces bone resorption. The presence of induced cholesteatoma and determination of actual bone resportion will be determined histologically and with special staining techniques.